BEL AIR, Maryland (AP) — Immigration advocates are swarming the U.S. this month, trying to persuade House Republicans to pass a comprehensive overhaul.

For all the effort that business and labor groups, activists and others who support action on immigration say they’re pouring into making themselves heard during Congress’ five-week summer recess, there are scores of House Republicans who are hearing very little of the clamor.

These lawmakers are insulated in safe districts where immigration activists don’t bother to venture, or so hardened in their positions that no one’s even trying to change their minds.

“Most of the energy is being spent on the folks who are gettable,” said Frank Sharry, executive director of America’s Voice, a pro-immigrant group. “We’re not spending a lot of time on Republicans who are clearly going to vote ‘no.’”

With immigration legislation stuck in limbo in the Republican-led House of Representatives, that reality raises the question of how successful advocates can be in reaching their goal for this month: generating enough momentum to propel Congress to act when lawmakers return to Washington in September.

For now, immigration legislation is stalled following Senate passage with bipartisan support in June of a comprehensive bill with billions for border security, changes to visa programs and a new focus on workplace enforcement, plus eventual access to citizenship for the 11 million immigrants already in the country illegally.

House Republicans overwhelmingly oppose the Senate bill. Many don’t want to grant citizenship to people who broke U.S. laws to be here. Instead of a single big bill, they prefer a step-by-step approach, beginning with border security.

But any action even on that is not expected until October at the earliest because Congress has only nine legislative days in September and they are expected to be devoted to fiscal issues. So far, no House committee has advanced legislation that would offer a path to citizenship to anyone here illegally.

The challenge facing immigration reform advocates in gaining support among House Republicans was evident at a town-hall meeting that second-term Republican Rep. Andy Harris held recently in the town of Bel Air, Maryland, northeast of Baltimore.

The overflow crowd in the board of commissioners meeting room was overwhelmingly white and older, and booed loudly when one audience member asked Harris to support a path to citizenship for immigrants who are in the U.S. illegally.

“The bottom line is there are plenty of immigration laws on the books,” Harris said. “The House is in no rush to take up immigration.”

Harris, a 56-year-old physician and the son of Eastern European immigrants, is in a safe Republican district with few Latino voters, and he’s not on target lists drawn up by immigration proponents. So it’s no surprise that advocates wouldn’t be out in force at his events.

Immigration advocates know they must change some minds among Republican lawmakers this month.

Of the 233 Republicans in the House, 121 are on a list of House Republican targets distributed last month by senators who support an immigration overhaul. House Speaker John Boehner has pledged only to advance immigration legislation supported by a majority of his Republican caucus, and advocates have identified a potential majority in support.

But that target list includes a number of long shots. Advocates involved with the umbrella group Alliance for Citizenship are focusing on 50 districts where they view the lawmakers as more realistically persuadable and say they are undertaking aggressive on-the-ground campaigns.

A week into lawmakers’ summer recess, immigration advocates are trumpeting comments from a few Republicans, including Daniel Webster of Florida, Aaron Schock of Illinois and Dave Reichert of Washington state, indicating qualified support for eventual citizenship for those in the country illegally.

It’s unclear whether such developments are limited to a small number of lawmakers, including some in districts with changing demographics or a more moderate electorate, or whether they become widespread enough to compel House Republicans to act on a far-reaching package of immigration bills that could be merged with the Senate-passed measure and sent to President Barack Obama.

The answer may determine the way forward in Congress for immigration legislation, and whether Obama will achieve one of his chief second-term priorities.

“These Republican members are reflecting their constituents, so the challenge isn’t pressuring the Republican members, the challenge is to come up with a convincing and compelling argument for their constituents to agree to,” said Republican pollster David Winston, who advises House Republicans.

As for the endgame in the House, Winston said, “I don’t know that that’s clear yet, and part of what this August interaction with the electorate is going to be about is to define what that looks like.”

Immigration advocates say their efforts are getting results. They point to Schock’s announcement at a recent town-hall meeting that he supports a path to citizenship with certain conditions, and similar statements from Reichert and Webster, among others.

Rebecca Shi, organizing director for the Illinois Coalition for Immigrant and Refugee Rights, said Schock was lobbied by businesses in his district, as well as donors, religious leaders and others before making his declaration under questioning from an activist who said she was in the country illegally.

America’s Voice says those recent announcements bring to more than 20 the number of Republican House members who have indicated some kind of support for citizenship.

It’s a position backed by majorities of voters in most nationwide polls. But the story is different in many Republican House districts, which often have few Latino voters and are drawn to make them safe for Republican candidates.

In Harris’ district, which is less than 5 percent Latino and includes towns north of Baltimore and Maryland’s Eastern Shore, some residents said they strongly oppose citizenship for those here illegally.

“We’re in competition with millions of illegal aliens,” said Ed Hunter, 55, of Easton, after attending Harris’ town hall. “The law should be enforced. They should be deported.”

Despite the efforts of advocates, it is often those kinds of sentiments that Republicans around the country are hearing.

Some Republican senators have expressed concern that failure to advance immigration reform legislation will hurt Republican candidates in statewide and national elections in gaining support among the rapidly growing Hispanic demographic. About 70 percent of Hispanic voters supported Obama in last year’s presidential election.

But many House Republicans in safe districts fear that creating millions of new Latino citizens will boost support for Democratic candidates.